Prominent environmental leaders, including the head of the Sierra Club, were arrested Wednesday after tying themselves to the White House gate to protest the Keystone XL oil pipeline.

The protesters demand that President Barack Obama reject the pipeline, which they say would carry “dirty oil” that contributes to global warming.

Executive Director Michael Brune is the first Sierra Club leader in the group’s 120-year history to be arrested in an act of civil disobedience. The club’s board of directors approved the action as a sign of their opposition to the $7 billion pipeline, which would carry oil derived from tar sands in western Canada to refineries along the Texas Gulf Coast.

Robert F. Kennedy Jr., the president of Waterkeeper Alliance, was arrested along with his son, Connor, the 18-year-old ex-boyfriend of singer Taylor Swift. In an emailed statement from his organization, Robert F. Kennedy Jr. said “It’s unfortunate that civil disobedience is the only recourse against a catastrophic and criminal enterprise that will enrich a few while impoverishing the rest of humanity and threatening the future of civilization.”

Along with the Kennedys, 350.org founder Bill McKibben, and actress Daryl Hannah were also arrested. Hannah was previously arrested for separate Keystone pipeline protests in Texas last October and at the White House in August 2011.

McKibben said in a statement from Tar Sands Action, “We really shouldn’t have to be put in handcuffs to stop KXL–our nation’s leading climate scientists have told us it’s dangerous folly, and all the recent Nobel Peace laureates have urged us to set a different kind of example for the world, so the choice should be obvious.”

In all, 48 environmental, civil rights, and community leaders from across the country joined together for a historic display of civil disobedience at the White House, where they were arrested on Wednesday after they handcuffed themselves to the fence.